<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title></title>
    <script>
    function show(...args){
      fn(...args);
    }

    function fn(a, b){
      alert(a+b);
    }

    show(12, 5);
    </script>
  </head>
  <body>

  </body>
</html>
